An explosion hit a Japanese oil tanker in the early hours of Wednesday in the Strait of Hormuz near Iran and Oman, and the crew attributed the blast to an attack, the transport ministry said.
One crew member was injured and the ship, belonging to Mitsui OSK Lines, was partly damaged but able to continue sailing after the blast hit at 00:30 am local time (2030 GMT Tuesday), the Japanese ministry said.
"Since one of the crew saw a flash on the horizon immediately before the blast, the company suspects it was highly likely an attack," the transport ministry said, adding that the area was not known for commercial piracy.
The vessel -- staffed by 16 crew from the Philippines and 15 Indians -- was carrying 270,000 tones of crude oil but did not suffer a spill.
The tanker was heading from the United Arab Emirates to the Japanese port of Chiba, east of Tokyo, at the time of the blast, the ministry said.
The Strait of Hormuz links the Gulf -- including the ports of oil-rich states such as Kuwait, Bahrain and Qatar -- with the Arabian Sea, making it a highly strategic conduit for global energy supplies.
The cause for the explosion was "maybe an attack, not a spontaneous accident, it may be a terrorist attack," Junto Endoh, general manager in the Doha liaison office for Mitsui OSK Lines, told Dow Jones Newswires.
"The vessel is now navigating towards Fujairah by itself," he said, referring to an emirate in the United Arab Emirates, adding that the explosion on the tanker had not been "huge", said Dow Jones.